A number of devices and methods have been used in the past to detect arc faults. Some of the prior art devices and techniques have involved the use of E and B field arc sensors, the detection of the amplitude of arc fault rate of change of current signals, the use of non-overlapping band-pass filters to detect white noise of arcs, and devices which detect the disappearance of arc faults near current zero crosses. Most of the prior art of arc detection occurs in circuit breakers where it acts as an enhancement to thermal-magnetic detection elements, which alone may fail to detect arc faults. To date, all of the circuit breaker arc fault detectors protect primarily building wiring up to the outlet but only offer limited protection for lamp and extension cords. This invention identifies particular patterns of arc fault noise sensed in the load current during arc faults which are particular to arc faults only. This invention also is intended for a receptacle embodiment which can protect downstream building wiring as well as the arcing that may occur in lamp cords or extension cords and also provide limited protection of upstream building wiring.
There is a need for an economical arc fault detector which may be mounted into a wiring device which offers the same down stream protection as an arc fault detecting circuit breaker but at the similar cost advantage that currently exist between ground fault interrupting receptacles and ground fault interrupting circuit breakers. A receptacle arc fault detector has the additional advantage of being universally adaptable to any wiring system, which is in contrast to circuit breaker arc fault detectors which are specific to a particular panel box manufacturer. This invention provides that cost and universal mounting advantage.